Embodiments of the present disclosure generally relate to methods and devices for estimating a duration of a QRS complex based on intracardiac electrograms signals.
Implantable medical device programmable cardiac resynchronization therapy (CRT) based on various parameters. Changes in the CRT parameters have been shown to have an impact on clinical outcomes. Nonlimiting examples of CRT parameters include atrioventricular and interventricular activation delays (AVD and VVD, respectively), electrode configuration, and selection of paced ventricular chambers. Identifying a desired set of CRT parameters relies on an accurate assessment of relative cardiac function. Echocardiography and invasive left ventricular (LV) pressure measurements have been considered the gold standard for direct, comprehensive hemodynamic optimization of CRT parameters. However, echocardiography and LV pressure measurements are costly, time consuming, and must occur in a clinical environment.
Separately, surface electrocardiogram (ECG) signals have been utilized as a simpler alternative for assessing relative cardiac function. ECG signals may be utilized to determine whether electrical synchrony has been restored by CRT. More specifically, an ECG signal may be analyzed for a broad or narrow QRS complex. Dyssynchrony is typically associated with a broad QRS complex, while synchrony is typically associated with a narrow QRS complex.
However, the cardiovascular status of an individual patient constantly changes. Accordingly, continuous evaluation of, and adaptation to, the current cardiovascular status is necessary in order to maintain an optimal CRT parameter set. The use of surface ECG electrodes to collect ECG sisals represents a cumbersome, time-consuming and difficult system to provide continuous, ambulatory monitoring of the cardiac response to CRT.